Greg Heffley tells about his summer vacation and his attempts to steer clear of trouble when he returns to middle school and tries to keep his older brother Rodrick from telling everyone about Greg's most humiliating experience of the summer.

Greg Heffley recounts his daily experiences during summer vacation as he tries to live out his ultimate fantasy of spending the days indoors playing video games with no responsibilities and no rules, despite his mother's attempts to pack the summer with outdoor activities and family fun.

Bub the pug has never seen snow before, and when Duchess the cat tells him it is frozen rain he is appalled and does not want to go out even to play with his human, Bella--but the week is about to get worse because a new family has moved in next door, and they apparently have a pet monster (at least if Nutz the squirrel can be believed) and Bella's mother has arranged a play date for Sunday.

Up until now, middle school hasn't exactly been a joyride for Greg Heffley. So when the town threatens to close the crumbling building, he's not too broken up about it. But when Greg realizes this means he's going to be sent to a different school than his best friend, Rowley Jefferson, he changes his tune. Can Greg and his classmates save their school before it's shuttered for good? Or is this the start of a whole new chapter for Greg?